Vehicles such as automobiles are provided with a heat storage apparatus that temporarily stores surplus heat from heat sources of the vehicles in a heat storage body, and releases and uses the heat stored in the heat storage body for heating temperature adjustment sections of the vehicles and the like. In such a heat storage apparatus, employing a heat storage body capable of latent heat storage as the foregoing heat storage body is effective in increasing the amount of heat storage in the heat storage body while keeping the capacity of the heat storage body low. Latent heat storage refers to heat storage utilizing absorption and release of heat in/from a material forming the heat storage body with state changes of the material (for example, changes between solid and liquid states).
FIG. 6 shows a relationship between changes in state of a heat storage body capable of latent heat storage and changes in temperature of the heat storage body.
As understood from the drawing, if heat from a heat source of a vehicle is provided to a heat storage body in a solid state, the temperature of the heat storage body increases and reaches a melting point T. After that, if heat is continuously provided to the heat storage body, the heat storage body gradually changes from a solid state to a liquid state at an almost constant temperature. Then, if the heat storage body entirely changes to a liquid state, the temperature of the heat storage body begins to increase again due to the provision of heat.
On the other hand, if the heat stored in the heat storage body in a liquid state is used for heating a temperature adjustment section of the vehicle, the heat stored in the heat storage body is released. When the heat is thus released from the heat storage body, the temperature of the heat storage body decreases from a value higher than the melting point T to the melting point T. After that, if the heat is continuously released from the heat storage body, the heat storage body gradually changes from a liquid state to a solid state at an almost constant temperature. Then, when the heat storage body entirely changes to a solid state, the temperature of the heat storage body begins to decrease again due to the release of heat.
When heat is stored in the heat storage body in a solid state, the heat storage body is in a sensible heat storage state and therefore the heat storage apparatus performs sensible heat storage. In addition, when the heat storage body enters a liquid state, in other words, the heat storage body enters a latent heat storage state, due to application of heat to the heat storage body, the heat storage apparatus performs latent heat storage. To retain the heat storage state of the heat storage apparatus for a long period of time, it is preferred to keep the heat storage body in the latent heat storage state. Accordingly, in the heat storage apparatus equipped with a heat storage body capable of latent heat storage, it is desired that the heat storage body is kept in the latent heat storage state as much as possible.
To realize this, Patent Document 1 discloses that a heat storage body is separated into a plurality of parts, and heat from a heat source of a vehicle is applied to the separated heat storage parts in order at the time of heat storage. Specifically, heat from the heat source of the vehicle is selectively applied to the separated heat storage parts so as to enter them one by one into the latent heat storage state. In this case, when heat from the heat source of the vehicle is applied to the heat storage parts for heat storage in the heat storage parts, it is possible to enter promptly at least a part of the heat storage body into the latent heat storage state. If at least a part of the heat storage body can be entered into the latent heat storage state in such a manner as described above, it is possible to keep the heat storage apparatus in the heat storage state for a longer period of time.